The type certification basis includes exemptions, if any; equivalent level of safety findings, if any; and the special conditions adopted by this rulemaking action.

If the Administrator finds that the applicable airworthiness regulations (i.e., part 23) do not contain adequate or appropriate safety standards for the Piper Model PA28236 airplanes with the installation of an SMA Model SR305230 ADE because of a novel or unusual design feature, special conditions are prescribed under the provisions of Sec. 21.16.

In addition to the applicable airworthiness regulations and special conditions, the Piper Model PA28236 airplanes, with the installation of an SMA Model SR305230 ADE, must comply with 14 CFR 21.115 noise certification requirements of 14 CFR part 36.

Special conditions, as appropriate, as defined in 11.19, are issued in accordance with Sec. 11.38, and become part of the type certification basis in accordance with Sec. 21.101.

Special conditions are initially applicable to the model for which they are issued. Should the applicant apply for a supplemental type certificate to modify any other model included on the same type certificate to incorporate the same novel or unusual design feature, the special conditions would also apply to the other model under the provisions of Sec. 21.101.

Novel or Unusual Design Features

The Piper Model PA28236 airplanes, with the installation of an SMA Model SR305230 ADE, will incorporate the following novel or unusual design features: The Piper Model PA28236 airplanes, with the installation of an SMA Model SR305230, will incorporate an aircraft diesel engine utilizing turbine (jet) fuel.

Discussion of Comments

A notice of proposed special conditions No. 230603SC for Aero Propulsion, Inc., for the Piper Model PA28236 airplanes, with the installation of an SMA Model SR305230 ADE, was published on June 14, 2006 (71FR 34292). No comments were received, and the special conditions are adopted as proposed.

Applicability

As discussed above, these special conditions are applicable to the Piper Model PA28236 airplanes, with the installation of an SMA Model SR305230 ADE. Should Aero Propulsion, Inc., apply at a later date for a supplemental type certificate to modify any other model included on Type Certificate No.2A13 to incorporate the same novel or unusual design feature, the special conditions would apply to that model as well under the provisions of Sec. 21.101.

Conclusion

This action affects only certain novel or unusual design features on the Piper Model PA28236 airplanes, with the installation of an SMA Model SR305230 ADE. It is not a rule of general applicability, and it affects only the applicant who applied to the FAA for approval of these features on the airplane.
List of Subjects in 14 CFR Part 23

Aircraft, Aviation safety, Signs and symbols.
Citation
The authority citation for these special conditions is as follows:

Authority: 49 U.S.C. 106(g), 40113 and 44701; 14 CFR 21.16 and 21.101; and 14 CFR 11.38 and 11.19.
The Special Conditions
Accordingly, pursuant to the authority delegated to me by the Administrator, the following special conditions are issued to Aero Propulsion, Inc., as part of the type certification basis for the Piper Model PA28236 airplanes, with the installation of an SMA Model SR305 230 ADE.

1. Engine torque (Provisions similar to Sec. 23.361, paragraphs (b)(1) and (c)(3)):
(a) For diesel engine installations, the engine mounts and supporting structure must be designed to withstand the following: (1) A limit engine torque load imposed by sudden engine stoppage due to malfunction or structural failure.

The effects of sudden engine stoppage may alternately be mitigated to an acceptable level by utilization of isolators, dampers, clutches and similar provisions, so that unacceptable load levels are not imposed on the previously certificated structure.
(b) The limit engine torque obtained in CAR 3.195(a)(1) and (a)(2) or 14 CFR 23.361(a)(1) and (a)(2) must be obtained by multiplying the mean torque by a factor of four in lieu of the factor of two required by CAR 3.195(b) and 14 CFR 23.361(c)(3).

2. Flutter(Compliance with the requirements of Sec. 23.629 (e)(1) and (e)(2) requirements): The flutter evaluation of the airplane done in accordance with 14 CFR 23.629 must include
(a) Whirl mode degree of freedom which takes into account the stability of the plane of rotation of the propeller and significant elastic, inertial, and aerodynamic forces, and
(b) Propeller, engine, engine mount and airplane structure stiffness and damping variations appropriate to the particular configuration, and
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(c) The flutter investigation will include showing the airplane is free from flutter with one cylinder inoperative.

3. PowerplantInstallation (Provisions similar to Sec. 23.901(d)(1) for turbine engines): Considering the vibration characteristics of diesel engines, the applicant must comply with the following:
(a) Each diesel engine installation must be constructed and arranged to result in vibration characteristics that
(1) Do not exceed those established during the type certification of the engine; and
(2) Do not exceed vibration characteristics that a previously certificated airframe structure has been approved for
(i) Unless such vibration characteristics are shown to have no effect on safety or continued airworthiness, or
(ii) Unless mitigated to an acceptable level by utilization of isolators, dampers, clutches and similar provisions, so that unacceptable vibration levels are not imposed on the previously certificated structure.

4. PowerplantFuel SystemFuel system with water saturated fuel (Compliance with Sec. 23.951 requirements): Considering the fuel types used by diesel engines, the applicant must comply with the following:

Each fuel system for a diesel engine must be capable of sustained operation throughout its flow and pressure range with fuel initially saturated with water at 80 [deg]F and having 0.75cc of free water per gallon added and cooled to the most critical condition for icing likely to be encountered in operation.

Methods of compliance that are acceptable for turbine engine fuel systems requirements of Sec. 23.951(c) are also considered acceptable for this requirement.

5. PowerplantFuel SystemFuel flow (Compliance with Sec. 23.955(c) requirements): In lieu of 14 CFR 23.955(c), engine fuel system must provide at least 100 percent of the fuel flow required by the engine, or the fuel flow required to prevent engine damage, if that flow is greater than 100 percent. The fuel flow rate must be available to the engine under each intended operating condition and maneuver. The conditions may be simulated in a suitable mockup. This flow must be shown in the most adverse fuel feed condition with respect to altitudes, attitudes, and any other condition that is expected in operation.

6. PowerplantFuel SystemFuel system hot weather operation (Compliance with Sec. 23.961 requirements): In place of compliance with Sec. 23.961, the applicant must comply with the following:

Each fuel system must be free from vapor lock when using fuel at its critical temperature, with respect to vapor formation, when operating the airplane in all critical operating and environmental conditions for which approval is requested. For turbine fuel, or for aircraft equipped with diesel cycle engines that use turbine or diesel type fuels, the initial temperature must be 110 [deg]F, 0[deg], +5[deg] or the maximum outside air temperature for which approval is requested, whichever is more critical.

The fuel system must be in an operational configuration that will yield the most adverse, that is, conservative results.

To comply with this requirement, the applicant must use the turbine fuel requirements and must substantiate these by flighttesting, as described in Advisory Circular AC 238B, Flight Test Guide for Certification of Part 23 Airplanes.

7. PowerplantFuel systemFuel tank filler connection (Compliance with Sec. 23.973(f) requirements): In place of compliance with Sec. 23.973(e) and (f), the applicant must comply with the following:

For airplanes that operate on turbine or diesel type fuels, the inside diameter of the fuel filler opening must be no smaller than 2.95 inches.

8. PowerplantFuel systemFuel tank outlet (Compliance with Sec. 23.977 requirements): In place of compliance with Sec. 23.977(a)(1) and (a)(2), the applicant will comply with the following:

There must be a fuel strainer for the fuel tank outlet or for the booster pump. This strainer must, for diesel engine powered airplanes, prevent the passage of any object that could restrict fuel flow or damage any fuel system component.

9. EquipmentGeneralPowerplant Instruments (Compliance with Sec. 23.1305): In addition to compliance with Sec. 23.1305, the applicant will comply with the following:

The following are required in addition to the powerplant instruments required in Sec. 23.1305:
(a) A fuel temperature indicator.
(b) An outside air temperature (OAT) indicator.
(c) An indicating means for the fuel strainer or filter required by Sec. 23.997 to indicate the occurrence of contamination of the strainer or filter before it reaches the capacity established in accordance with Sec. 23.997(d).

Alternately, no indicator is required if certain requirements are met. First, the engine can operate normally for a specified period with the fuel strainer exposed to the maximum fuel contamination as specified in MIL5007D. Second, provisions for replacing the fuel filter at this specified period (or a shorter period) are included in the maintenance schedule for the engine installation.

10. Operating Limitations and InformationPowerplant limitations Fuel grade or designation (Compliance with Sec. 23.1521 requirements): All engine parameters that have limits specified by the engine manufacturer for takeoff or continuous operation must be investigated to ensure they remain within those limits throughout the expected flight and ground envelopes (e.g., maximum and minimum fuel temperatures, ambient temperatures, as applicable, etc.). This is in addition to the existing requirements specified by 14 CFR 23.1521 (b) and (c). If any of those limits can be exceeded, there must be continuous indication to the flight crew of the status of that parameter with appropriate limitation markings.

Instead of compliance with Sec. 23.1521(d), the applicant must comply with the following:

The minimum fuel designation (for diesel engines) must be established so that it is not less than that required for the operation of the engines within the limitations in paragraphs (b) and (c) of Sec. 23.1521.

11. Markings and PlacardsMiscellaneous markings and placards Fuel, oil, and coolant filler openings (Compliance with Sec. 23.1557(c)(1) requirements): Instead of compliance with Sec. 23.1557(c)(1), the applicant must comply with the following:

Fuel filler openings must be marked at or near the filler cover with

For diesel enginepowered airplanes
(a) The words ``Jet Fuel''; and
(b) The permissible fuel designations, or references to the Airplane Flight Manual (AFM) for permissible fuel designations. (c) A warning placard or note that states the following or similar: ``Warningthis airplane equipped with an aircraft diesel engine, service with approved fuels only.''

The colors of this warning placard should be black and white.

12. PowerplantFuel systemFuelFreezing: If the fuel in the tanks cannot be shown to flow suitably under all possible temperature conditions, then fuel temperature limitations are required. These will be considered as part of the essential operating
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parameters for the aircraft and must be limitations.

A minimum takeoff temperature limitation will be determined by testing to establish the minimum coldsoaked temperature at which the airplane can operate. The minimum operating temperature will be determined by testing to establish the minimum operating temperature acceptable after takeoff from the minimum takeoff temperature. If low temperature limits are not established by testing, then a minimum takeoff and operating fuel temperature limit of 5 [deg]F above the gelling temperature of Jet A will be imposed along with a display in the cockpit of the fuel temperature. Fuel temperature sensors will be located in the coldest part of the tank if applicable.

13. Powerplant InstallationVibration levels: Vibration levels throughout the engine operating range must be evaluated and: (1) Vibration levels imposed on the airframe must be less than or equivalent to those of the gasoline engine; or
(2) Any vibration level that is higher than that imposed on the airframe by the replaced gasoline engine must be considered in the modification and the effects on the technical areas covered by the following paragraphs must be investigated:

14 CFR part 23, Sec. Sec. 23.251; 23.613; 23.627; 23.629 (or CAR 3.159, as applicable to various models); 23.572; 23.573; 23.574 and 23.901.

Vibration levels imposed on the airframe can be mitigated to an acceptable level by utilization of isolators, dampers, clutches and similar provisions, so that unacceptable vibration levels are not imposed on the previously certificated structure.

14. Powerplant InstallationOne cylinder inoperative: It must be shown by test or analysis, or by a combination of methods, that the airframe can withstand the shaking or vibratory forces imposed by the engine if a cylinder becomes inoperative. Diesel engines of conventional design typically have extremely high levels of vibration when a cylinder becomes inoperative.

No unsafe condition will exist in the case of an inoperative cylinder before the engine can be shut down. The resistance of the airframe structure, propeller, and engine mount to shaking moment and vibration damage must be investigated. It must be shown by test or analysis, or by a combination of methods, that shaking and vibration damage from the engine with an inoperative cylinder will not cause a catastrophic airframe, propeller, or engine mount failure.

15. Powerplant InstallationHigh Energy Engine Fragments: It may be possible for diesel engine cylinders (or portions thereof) to fail and physically separate from the engine at high velocity (due to the high internal pressures). This failure mode will be considered possible in engine designs with removable cylinders or other nonintegral block designs. The following is required:
(1) It must be shown by the design of the engine, that engine cylinders, other engine components or portions thereof (fragments) cannot be shed or blown off of the engine in the event of a catastrophic engine failure; or
(2) It must be shown that all possible liberated engine parts or components do not have adequate energy to penetrate engine cowlings; or (3) Assuming infinite fragment energy, and analyzing the trajectory of the probable fragments and components, any hazard due to liberated engine parts or components will be minimized and the possibility of crew injury is eliminated. Minimization must be considered during initial design and not presented as an analysis after design completion.

Issued in Kansas City, Missouri on July 27, 2006. James E. Jackson,
Acting Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. E612663 Filed 8306; 8:45 am]
BILLING CODE 491013P

FOR FURTHER INFORMATION CONTACT Peter L. Rouse, Federal Aviation Administration, Aircraft Certification Service, Small Airplane Directorate, ACE111, 901 Locust, Kansas City, Missouri, 8163294135, fax 8163294090.